Add first pass at a JavaScript lexer.

2 files changed, 75 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 191f12b..e059e0f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,6 +44,7 @@ SOURCES =					\
   syntax-highlight/c.scm			\
   syntax-highlight/css.scm			\
   syntax-highlight/gitignore.scm		\
+  syntax-highlight/javascript.scm		\
   syntax-highlight/lisp.scm			\
   syntax-highlight/scheme.scm			\
   syntax-highlight/xml.scm			\
diff --git a/syntax-highlight/javascript.scm b/syntax-highlight/javascript.scm
new file mode 100644
index 0000000..544c213
--- /dev/null
+++ b/syntax-highlight/javascript.scm
@@ -0,0 +1,74 @@
+;;; guile-syntax-highlight --- General-purpose syntax highlighter
+;;; Copyright © 2023 David Thompson <davet@gnu.org>
+;;;
+;;; Guile-syntax-highlight is free software; you can redistribute it
+;;; and/or modify it under the terms of the GNU Lesser General Public
+;;; License as published by the Free Software Foundation; either
+;;; version 3 of the License, or (at your option) any later version.
+;;;
+;;; Guile-syntax-highlight is distributed in the hope that it will be
+;;; useful, but WITHOUT ANY WARRANTY; without even the implied
+;;; warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+;;; See the GNU Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with guile-syntax-highlight.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Syntax highlighting for JavaScript.
+;;
+;;; Code:
+
+(define-module (syntax-highlight javascript)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
+  #:use-module (syntax-highlight lexers)
+  #:export (lex-javascript))
+
+(define %js-reserved-words
+  '("async" "await" "break" "case" "catch" "class" "const" "continue"
+    "debugger" "default" "delete" "do" "else" "export" "extends" "false"
+    "finally" "for" "function" "if" "import" "in" "instanceof" "let" "new"
+    "null" "return" "static" "super" "switch" "this" "throw" "true" "try"
+    "typeof" "var" "void" "while" "with" "yield"))
+
+(define (js-reserved-word? str)
+  (any (cut string=? <> str) %js-reserved-words))
+
+(define %js-operators
+  '(";" "," "." "?." "..." "#" "=" "+=" "-=" "*=" "/=" "%=" "<<=" ">>="
+    ">>>=" "&=" "^=" "|=" "**=" "&&=" "||=" "??=" "?" ":" "||" "&&" "??"
+    "|" "^" "&" "~" "==" "===" "!=" "!==" "<=" ">=" "<" ">" "<<" ">>" ">>>"
+    "*" "/" "%" "!" "++" "--" "+" "-" ))
+
+(define lex-js-operator
+  (lex-any* (map lex-string %js-operators)))
+
+;; A rough approximation of characters that are allowed in Javascript
+;; variables, numbers, etc.
+(define char-set:js-identifier
+  (char-set-adjoin char-set:letter+digit #\$ #\_))
+
+(define lex-js-identifier
+  (lex-char-set char-set:js-identifier))
+
+;; TODO: Highlight regexp literals.
+(define lex-javascript
+  (lex-consume
+   (lex-any (lex-char-set char-set:whitespace)
+            (lex-tag 'open (lex-any* (map lex-string '("(" "[" "{"))))
+            (lex-tag 'close (lex-any* (map lex-string '(")" "]" "}"))))
+            (lex-tag 'comment (lex-any (lex-delimited "//" #:until "\n")
+                                       (lex-delimited "/*" #:until "*/")
+                                       (lex-delimited "#!" #:until "\n")))
+            (lex-tag 'special (lex-filter js-reserved-word? lex-js-identifier))
+            (lex-tag 'operator lex-js-operator)
+            (lex-tag 'string (lex-any (lex-delimited "\"")
+                                      (lex-delimited "'")))
+            ;; TODO: Highlight expressions within template literals.
+            (lex-tag 'template (lex-delimited "`"))
+            (lex-tag 'symbol lex-js-identifier))))